Scientists have offered the illustration of a rapidly moving wheel, top, or cylinder, to show the effects of increasing rates of vibration. The illustration supposes a wheel, top, or revolving cylinder, running at a low rate of speed--we will call this revolving thing "the object" in following out the illustration. Let us suppose the object moving slowly. It may be seen readily, but no sound of its movement reaches the ear. The speed is gradually increased. In a few moments its movement becomes so rapid that a deep growl or low note may be heard. Then as the rate is increased the note rises one in the musical scale. Then, the motion being still further increased, the next highest note is distinguished. Then, one after another, all the notes of the musical scale appear, rising higher and higher as the motion is increased. Finally when the motions have reached a certain rate the final note perceptible to human ears is reached and the shrill, piercing shriek dies away, and silence follows. No sound is heard from the revolving object, the rate of motion being so high that the human ear cannot register the vibrations. Then comes the perception of rising degrees of Heat. Then after quite a time the eye catches a glimpse of the object becoming a dull dark reddish color. As the rate increases, the red becomes brighter. Then as the speed is increased, the red melts into an orange. Then the orange melts into a yellow. Then follow, successively, the shades of green, blue, indigo, and finally violet, as the rate of sped increases. Then the violet shades away, and all color disappears, the human eye not being able to register them. But there are invisible rays emanating from the revolving object, the rays that are used in photographing, and other subtle rays of light. Then begin to manifest the peculiar rays known as the "X Rays," etc., as the constitution of the object changes. Electricity and Magnetism are emitted when the appropriate rate of vibration is attained.